It looks like the kind of simple setup you'd see in an Ikea showroom. But the model house built this week at Tempe Town Lake spotlights German innovations so advanced that they slash household energy use by at least 90 percent.

It looks like the kind of simple setup you'd see in an Ikea showroom. But the model house built this week at Tempe Town Lake spotlights German innovations so advanced that they slash household energy use by at least 90 percent.

As the last truck pulls away and the hardhats come off, 20 solar-powered houses built by university students and associates from around the world will open to the public Friday on the National Mall. The Department of Energy challenged students in the third biennial Solar Decathlon to build their own 800-square-foot homes that offer the style and comfort consumers want and the energy efficiency the world needs.

The University of Colorado is once again the winner of the Solar Decathlon, sponsored by the Department of Energy. Eighteen college teams built solar-energy houses that were displayed until Sunday on the National Mall in Washington, D.C.